Associate professor of nutritional sciences, University of Wisconsin-Madison, United States
6 diciembre 2010 | EN
This letter is in response to the feature article entitled Biofortified crops ready for developing world debut. While the article is generally well-written, a more negative picture of biofortification is given than is warranted. Having worked on provitamin A biofortification efforts since 2004 at the University of Wisconsin-Madison, I would like to correct some of these misrepresentations.
First the phrase "unleashed on" gives the impression that things are not being controlled. In fact the release of seed or vines to farmers is a highly regulated process and includes the following steps: 1) wide-scale screening to identify or develop lines with a high concentration of the desired nutrient for breeding biofortified cultivars, 2) crossing elite types with these sources, 3) selecting new types that combine high levels of the nutrient with excellent yield and other agronomic traits, 4) extensive testing and validation of the performance of the best lines, 5) validation of the suitability for use in food products, and 6) registration and commercialisation of the new variety in the target country. The crops that HarvestPlus is working with are going through this thorough process.
Second, large-scale studies to evaluate effectiveness cannot be performed until a crop like orange maize goes through these steps and is released. However, studies have already shown that orange maize is perceived differently and more favourably than yellow maize (which is associated with food aid or animal feed). Regarding orange sweet potato, which is the first biofortified crop to be released, a small-scale trial that showed it was effective in increasing serum retinol levels in children was conducted and published in the Journal of Nutrition. The author is referring to a larger-scale effectiveness trial that has yet to be published.
Third, the author incorrectly states, "the bioavailability of crops containing beta-carotene degrades once they have been harvested." It is not the bioavailability that degrades, it is the beta-carotene. However, it is not just the nutrients in biofortified crops that degrade, it is all nutrients in foods, including those in supplements. This is a natural process due to the chemical nature of vitamins. In fact, crops, such as sweet potato, are preferably eaten fresh; therefore, natural degradation may have little impact on effectiveness.
Fourth, the comparison of the cost of biofortification efforts to those of other interventions is potentially misleading. While the estimated cost per crop may seem high, the cost to distribute vitamin A supplements is upwards of $500 million — every six months. Furthermore, while effective at preventing overt clinical signs of vitamin A deficiency, supplements do not prevent a marginal status, which does not manifest as clinical signs but does not support optimal health, and the body needs a constant input of vitamin A in order to maintain adequate levels in essential organs. Biofortification can be effective as part of a strategy to reduce micronutrient deficiency that also includes supplementation and other approaches.
Last, I would disagree that HarvestPlus is taking an excessively top-down approach. To the contrary, farmers’ needs are accounted for as crops are being developed, and farmers participate in trials to test and select the best varieties. Orange sweet potato, in addition to delivering vitamin A, has been bred to be high yielding, virus resistant, and drought tolerant, all characteristics desired by farmers. Once crops have been disseminated successfully in one country, they can then be adapted to other regions at a low additional cost. Also, HarvestPlus' biofortified crops are given free to governments, and because these are crops eaten by poor and often malnourished communities, it is evident that they will only be taken up and have impact if they are free or affordable. While it is true that tackling social and economic issues are also part of the solution, nutritious food is a basic right to all humans. Biofortification of staple crops with enhanced nutrients is one way to provide the poor with an additional option for eating more nutritious foods. The process of enhancing crops, whether for taste, yield, or now nutrition, has been occurring since humans started farming.
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